&40 Mr H. Blackadder on the Action of certain Fluids on 
midity of the atmosphere exerted, in such cases ; though, it must 
be admitted, that the method which he proposed to determine 
the extent of the effect, was too limited to answer the end in 
view, as well as too complex to be of any practical use, even if it 
had possessed a greater degree of precision and generality than 
can be claimed for it. If the corrections, which I have suggest- 
ed, shall still be found defective, in the extreme cases, to which 
the common rules are inapplicable, the failure must be ascribed, 
in part, at least, to the difficulty of the subject, — a difficulty 
which neither the analytical resources of a La Place, nor the 
refined researches of a Playfair, were able altogether to over- 
come. 
Art. V. — On the Action of Certain Fluids on Hydrhophic Sub- 
stances of an Animal and Vegetable origin.' — By Henry 
Home Blackadder, Esq. Surgeon. 
Some years ago, I had occasion to make numerous experi- 
ments for the purpose of ascertaining the relative powers of hy- 
drhophic * bodies, and the effects produced on them by the ac- 
tion of various fluids. In the course of this investigation, cer- 
tain facts presented themselves, which, so far as I know, are 
new, and certainly not destitute of interest. It is to one of 
these facts that I mean at present more particularly to advert. 
In prosecuting this inquiry, it was considered of importance to 
distinguish bodies not only as being of mineral, vegetable, or 
animal origin, but also as being natural or artificial ; that is, 
such as they are found in nature, or modified only by a simply 
mechanical operation, and such as have been formed from na- 
tural substances by some process differing more or less from a 
simply mechanical operation. 
In examining the effects of different liquids on hydrhophic bo- 
dies of an animal and vegetable origin, I was desirous of ascer- 
taining not only the quantity of fluids absorbed, and the conse- 
quent increase of volume, but also the decrement of cohesion 
that resulted. Among other fluids, oils of various kinds at- 
* The term hydrhophic is intended to characterize those solid bodies which have 
the faculty of absorbing water, whether liquid or in the state of vapour. 
